The present invention refers to a temple for holding or for laterally tensioning a woven fabric, in particular on weaving looms, comprising endless guide means having displaceably arranged therein members provided with needles for engagement with said woven fabric, said guide means extending and being arranged in such a way that the needles of at least two members are simultaneously in engagement with the edge of the woven fabric and that, in the course of the needling-in operation, the needles brought into engagement with the woven fabric are located at a greater distance from the longitudinal axis of the width of woven fabric than in the course of the de-needling operation. The temples can be used on textile machines of all types through which widths of woven fabric pass, such as stenter, steaming, shrinking, drying, setting and dressing machines.
Temples generally have to fulfil the task of preventing the woven fabric from shrinking in transverse direction. In the case of weaving looms, temples are provided immediately after the weaving reed, especially for avoiding that damage is caused to the weaving reed and to the warp due to a change in the direction of the warp.
The general problem in the case of temples is to be seen in the fact that such temples have to take up a high transverse tension, but that any marks which may be caused by said temples on the woven fabric are to be avoided and that, in particular, the occurrence of torn pin holes is to be avoided.
A great variety of temples has already become known. In the case of a first type, the expander extends over the entire breadth of the width of fabric and it extends parallel to the weft threads. In this case, the woven fabric is normally guided such that it is partially wound round thread or porcupine cylinders. The main disadvantage of such temples are to be seen in a non-uniform transverse tension as well as in the fact that they are expensive and complicated and, in most cases, difficult to handle.
Another type of temples are the socalled cylinder temples, which are known, for example, from German-pat. 84 472 or from German-Offenlegungsschrift 22 53 364. These cylinder temples are attached to the selvages on the right- and on the left-hand side, the axes of said cylinders extending respectively parallel to the weft threads. Radially or obliquely extending spiked wheels, which are brought into engagement with the woven fabric, are arranged on said cylinders. These cylinder temples show the disadvantage that they produce only minor transverse tension, that the pin holes tear more frequently and that damage may also be caused to the edges of the fabric. German patents 20 310 and 30 372 also disclose socalled star-wheel temples in the case of which the star wheel is rotatably arranged in a plane parallel to the plane of the woven fabric and in the case of which the selvage is bent by 90.degree. and attached to the needles of the star wheel. The disadvantage of these star wheels is to be seen in the fact that the whole transverse tension is practically taken up by only a small number of needles so that the result practically is a point load. This may easily result in tearing of the pin holes.
In order to reduce the point load, German patents 9594 as well as 87 851 also disclose socalled chain temples in the case of which the chain revolved in a plane at right angles to the plane of the woven fabric or in a plane parallel to the weaving plane. With the aid of these chains, it can be achieved that the force of the transverse contraction of the woven fabric, which is to be taken up by the temple, can be distributed over a longer piece of the woven fabric. However, these chain temples on both sides of the width of woven fabric must be slightly inclined in the longitudinal direction of the width of woven fabric so as to reduce the transverse tension of the woven fabric at the outlet of the temple relative to the inlet of the temple adjacent the weaving reed to such an extent that de-needling of the woven fabric can be effected without causing any damage to said woven fabric. If the chain temples are adjusted such that they extend parallel to the selvages, there will be a great risk of tearing of the fabric at the outlet of the temple in the course of the de-needling operation.
However, due to the fact that the chain temples are inclined relative to the longitudinal axis of the width of woven fabric, the chain is also subjected to tension in the longitudinal direction. This causes stretching of the chain, and this will result in a large number of cases in which the chain is in need of repair as well as in a high amount of maintenance work, since the chain has to be retensioned extremely often with the aid of a chain adjuster.
Moreover, a chain temple shows additional disadvantages, which are to be seen in the fact that complicated screw connections have to be used for the individual combinations of members, in cases in which the chain has to be dismountable. Such a chain requires lubrication for smooth operation. This, however, is extremely difficult.
In order to avoid the disadvantages of a chain temple, while still utilizing its advantages, the applicant tried in tests to replace the respective chain by individual, independent members, which each carry needles and which are adapted to be displaced in a common endless guide means, a system which was, for example, already known from German patent specification 16 864. Although the members slided in the endless guide means excellently and easily, the temple, when used on a weaving loom, showed a tendency to blocking after a short period of time, whereas the members slided again without any problems after removal of the temple. Hence, additional tests were carried out in the case of which an enlarged amount of overall play between the members in the endless guide means was employed. However, in all cases mutual jamming of the members located on the return portion of the endless guide means occurred again after a short period of operation.
Hence, the present invention is based on the task of providing a temple of the type mentioned at the beginning, which permits smooth operation.
In accordance with the invention, this task is solved by the features that the members are supported such that they can be displaced relative to one another, that the overall amount of play between all members on the endless guide means is greater than or equal to the elongation of the woven fabric between the point of needling-in and the point of de-needling, and that there are provided means for holding the respective next member, which follows the member just carrying out the needling-in operation, in abutting contact with the member which is just carrying out the needling-in operation or which has just finished said operation, or within a maximum distance with regard to the member which is just carrying out the needling-in operation or which has just finished said operation.
Such an arrangement guarantees smooth operation without any jamming of the individual members, since it has been found out that, due to the inclination of the temples of known weaving mechanisms and the resultant narrowing of the width of woven fabric, the width of woven fabric will be subjected to lengthening or to an elongation in its longitudinal direction, and this lengthening or elongation will then cause jamming. The overall amount of play is assumed to be the sum of the distances between the members which are regarded as being non-compressible. If the distance between two neighbouring members is filled fully or partly with a material which is fully compressible in response to a compression pressure acting on the members, the distance between the members has to be regarded as the amount of play. In addition, an arrangement, in the case of which the demanded overall amount of play between the members is created only in response to a pressure on the members in their direction of movement due to an elastic deformation of the guide means, must be regarded as an equivalent embodiment as well.
In accordance with a preferred embodiment of the invention, there are provided at least two springs between respective pairs of juxtaposed members, said springs holding the respective members at such a distance from one another that the overall amount of play is distributed in a substantially uniform manner over the distances between the respective members, and that these two springs are provided between members which are substantially diametrically opposed on the guide path. Such an arrangement can be obtained in a comparatively easy way with the aid of pressure springs, although, in this connection, the disadvantage has to be accepted that, during the needling-in operation of the members, the distance remaining between the members having provided between them a spring will be greater than the distance remaining between the other members.
In accordance with another preferred embodiment of the invention, several or all members have attached thereto resilient buffer means, which hold the neighbouring members at a small distance from one another and which, in response to a certain amount of pressure acting on the members in the direction of sliding, are adapted to be compressed until the members mutually abut on one another. It is thus possible to distribute the overall amount of play provided between the members over the distances between all neighbouring members in a uniform manner when operation is being started so that the distance between two neighbourng members is comparatively small. An arrangement which proved to be particularly advantageous in this connection is an arrangement in the case of which each member has provided therein a recess which extends in the longitudinal direction of the member and which has inserted therein a piece of material having an e.g. rod-shaped configuration and consisting of a rubber material or a plastic material, said piece of material being of such a length that, when this buffer means abuts on the next following member and when no effect is produced by a compression force acting on the members, the members are located at a distance from one another which corresponds at least to the part of the overall amount of play obtained in the case of a uniform distribution of said overall amount of play among all neighbouring members. A buffer material which turned out to be particularly useful is polyurethane.
In accordance with an additional preferred embodiment of the invention, several or all neighbouring members are bevelled inwards towards the guide means on their sides facing one another,and a tappet member is arranged between respective pairs of neighbouring abutting members, said tappet member being, in response to a movement of the members, entrained and guided in the endless guide means, and in an area of the endless guide means in which the members are out of engagement with the width of woven fabric a cam path is provided, which springily projects in the path of movement of the tappet members and which, while said tappet members pass over said cam path, holds said tappet members in a position in which they are displaced relative to the neighbouring members and in which said tappet members hold the respective neighbouring members at a distance from one another. Said tappet members consist preferably of balls, cylinders or wedges. Such an arrangement has an extremely long service life and is practically maintenance-free.
It will be expedient when the cam path is formed by a ramp which is pretensioned by a spring and which, in response to a pressure acting in the direction of mutual abutting contact and applied to the members which are out of engagement with the width of woven fabric, can be displaced via the tappet members and against the force exerted by the spring to a position outside of the original path of movement of the tappel members. The amount of play between the members or between some members which are out of engagement with the width of woven fabric can thus arbitrarily be increased or reduced depending on the compression pressure acting on the members.
In accordance with an additional embodiment of the invention, a star wheel is provided having an axle which is supported such that it can be displaced in the direction of the endless guide means and which is springily pretensioned relative to said endless guide means, at least one star engaging between two neighbouring members, which are out of engagement with the width of woven fabric, for keeping said members at a distance from each other as long as excessive pressure is not applied to the members. Also such an arrangement can easily be realized and it has a long service life and is practically maintenance-free.
Another possible structural design of the present invention is that there is provided a slide member, which is adapted to be moved forwards and backwards along the members out of engagement with the width of woven fabric in step with the needling-in movement of a member and which engages behind a new member in the case of each backward motion, said slide member, when moving forward, applying a pressure to all the members which are positioned in front of it in the direction of movement so as to hold the next member, which follows the member just carrying out the needling-in operation, in abutting contact with said member just carrying out the needling-in operation. Actuation of the slide member can be effected by providing a rotatably supported star wheel which successively engages with a respective star thereof between two members which are in engagement with the width of woven fabric, and by providing a pivotably supported two-armed lever having one arm articulated on the slide member, which is springily pretensioned in its direction of movement, and having its other arm arranged such that it projects into the path of movement of the ends of the stars of the star wheel.
An arrangement which is practically independent of the different elongations occurring in the case of the different types of woven fabrics is an arrangement in the case of which there is provided a device for introducing a jet of compressed air in the direction of the forward movement of the members which are out of engagement with the width of woven fabric, said jet of compressed air being used for returning the respective members which have finished the de-needling operation into abutting contact with the member just carrying out the needling-in operation.